A cutting insert for grooving process or the like (hereinafter referred to as an “insert” in some cases) requires various functions, such as smooth discharge of generated chips, besides formation of a machined groove and width enlargement of the machined groove. In order to improve chip discharge performance, various considerations in the shape of a rake face of the insert have conventionally been made (for example, refer to Japanese Unexamined Patent Publication No. 6-8013).
However, in the insert described in Japanese Unexamined Patent Publication No. 6-8013, a plateau part 33 and a shoulder part 17, which are located at a higher position, exist behind a chip deflection surface 32. Therefore, there is a probability that chips generated from a workpiece having rich ductility cannot be smoothly discharged backward (outward).
Hence there is a desire for the insert allowing for excellent chip discharge property even when the workpiece is a material having rich ductility.